1. Field of the Invention
The present invention relates to a method for forming a protective film.
2. Description of the Related Art
Conventionally, as disclosed in Japanese Laid-Open Patent Application Publication No. 2010-103242, a method for manufacturing a semiconductor device is known. In the method, a LOCOS (LOCal Oxidation of Silicon) oxide film is formed on a surface of a silicon layer, and then an impurity region is formed by implanting impurity atoms into the silicon layer. Next, a SiN layer and a SiO2 layer are stacked on the silicon layer, and openings are selectively formed in the SiN layer and the SiO2 layer by photolithography and etching. Finally, trenches are formed in the LOCOS oxide film and the silicon layer by using the SiN layer and the SiO2 layer having the openings as a mask.
However, along with development of miniaturization in recent years, it has become difficult to accurately form a contact hole at a desired target position. Moreover, it has become difficult to make a mask to form the contact hole having the same size as the target. To solve these problems, it is necessary to form a protective film such that an area other than a desired portion is not etched even if an arraignment error occurs. However, it is very difficult to regionally leave the protective film due to a limitation of lithography accuracy. To solve these problems, it is desired to provide a method for forming a protective film in a self-aligning manner.